By Doug Young:New data is highlighting an online trend that I wrote about last year, namely that microblogs have peaked in popularity and are starting to decline, in a bad sign for leading web portal Sina (SINA) as it rushes monetize and list its popular Weibo service.

A little over a month after Chinese authorities moved to crack down on discussion of “Under The Dome,” the viral documentary which highlighted China’s pollution problem, and less than a week after Turkey banned social media after photos depicting now deceased prosecutor Mehmet Selim Kiraz with a gun to his head showed up on Facebook and Twitter, free sp

Social media is making its presence in felt in the financial world, with major household names like Facebook (FB) and Twitter (TWTR) already established as publicly-traded companies in the space. Not only are their stocks trading at high valuations, these companies have gone on an acquisition spree to widen their user bases and monetize them.

Alibaba, China’s biggest e-commerce company, just announced that it is paying $586 million for an 18% stake in Sina Weibo, the online ad company’s Twitter-like social media platform. Alibaba will have the option to raise its stake to 30% in the future.

China's Sina Corp plans to launch an English version of its popular Twitter-like microblogging service, a company spokesman was quoted saying Tuesday.The Chinese portal did not provide further details on the new service, Dow Jones Newswires said, and AFP calls to Sina were not answered.Sina chief executive Charles Chao said last month Weibo had more than 140 million registered users at the end of April and the company aimed to boost the number to "well beyond" 200 million by the end of the year.

By John Mylant: What does the softening of the Chinese economy mean for companies like the Sina Corporation (SINA)? Here you have a company that generates income through advertising for its 324 million registered users. It has the largest online Chinese community in the world. But advertising is drying up as corporations become more conservative how they spend on a weakening economy.

China's popular micoblogging site Weibo said it was tightening controls over its Twitter-like service, state press said Monday, amid concerns over growing government interference on the web.Chief executive officer of Sina -- Weibo's parent company -- Charles Chao said Sunday the measures were to curb the spread of malicious rumours on the service, China News Service reported."There are lots of false information and rumours on Weibo, and this will cause great challenges to the government as well as vendors on our platform," the report quoted Chao as saying.